: The investigators propose to study a large group of women, including women with pregnancy-induced hypertension that do not progress to preeclampsia as a control group. Longitudinal studies will monitor the occurrence and disappearance of T-cell skewing. They will determine if the hallmarks of a superantigen effect occur in preeclampsia: a) a robust activation of primary T cells; b) MHC class II-dependent response; and c) a TCR Vb-restricted response, in this case, Vb4+ T-cells. Studies will be initiated to define the source of the superantigen by challenging normal T-cells with plasma and syncytiotrophoblast microvillous membrane preparations from preeclamptic patients and monitoring T-cell skewing in vitro.